package factcheck

import (
	"context"
	"encoding/json"
	"errors"
	"strconv"
	"strings"
	"time"

	platformid "aigateway.local/core/internal/platform/id"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"
)

var ErrNotFound = errors.New("fact-check resource not found")

type Service struct{ pool *pgxpool.Pool }

func NewService(pool *pgxpool.Pool) *Service { return &Service{pool: pool} }

type Settings struct {
	ProviderID     *string   `json:"provider_id"`
	ProviderCode   string    `json:"provider_code"`
	Model          string    `json:"model"`
	TimeoutSeconds int       `json:"timeout_seconds"`
	UpdatedAt      time.Time `json:"updated_at"`
}

func (s *Service) Settings(ctx context.Context) (Settings, error) {
	var x Settings
	err := s.pool.QueryRow(ctx, `SELECT f.provider_id::text,coalesce(p.code,''),f.model,f.timeout_seconds,f.updated_at FROM gateway.fact_check_settings f LEFT JOIN gateway.providers p ON p.id=f.provider_id WHERE singleton`).Scan(&x.ProviderID, &x.ProviderCode, &x.Model, &x.TimeoutSeconds, &x.UpdatedAt)
	return x, err
}
func (s *Service) SaveSettings(ctx context.Context, x Settings, actor string) (Settings, error) {
	x.Model = strings.TrimSpace(x.Model)
	if x.TimeoutSeconds < 3 || x.TimeoutSeconds > 60 {
		return Settings{}, errors.New("超时必须在 3-60 秒之间")
	}
	if x.ProviderID != nil && strings.TrimSpace(*x.ProviderID) == "" {
		x.ProviderID = nil
	}
	if x.ProviderID != nil && x.Model == "" {
		return Settings{}, errors.New("配置供应商时模型不能为空")
	}
	_, err := s.pool.Exec(ctx, `UPDATE gateway.fact_check_settings SET provider_id=$1,model=$2,timeout_seconds=$3,updated_by=$4,updated_at=clock_timestamp() WHERE singleton`, x.ProviderID, x.Model, x.TimeoutSeconds, actor)
	if err != nil {
		return Settings{}, err
	}
	return s.Settings(ctx)
}

type Policy struct {
	ID                string    `json:"id"`
	Scope             string    `json:"scope"`
	Enabled           bool      `json:"enabled"`
	Mode              string    `json:"mode"`
	Action            string    `json:"action"`
	KnowledgeBaseIDs  []string  `json:"knowledge_base_ids"`
	SupportThreshold  int       `json:"support_threshold"`
	EvidenceThreshold float64   `json:"evidence_threshold"`
	TopK              int       `json:"top_k"`
	MaxClaims         int       `json:"max_claims"`
	Revision          int64     `json:"revision"`
	CreatedAt         time.Time `json:"created_at"`
	UpdatedAt         time.Time `json:"updated_at"`
}

func validatePolicy(x *Policy) error {
	x.Scope = strings.ToLower(strings.TrimSpace(x.Scope))
	if x.Scope == "" {
		x.Scope = "global"
	}
	if x.Mode == "" {
		x.Mode = "async"
	}
	if x.Action == "" {
		x.Action = "observe"
	}
	if x.Mode != "async" && x.Mode != "sync" {
		return errors.New("模式无效")
	}
	if x.Action != "observe" && x.Action != "annotate" && x.Action != "block" {
		return errors.New("处置动作无效")
	}
	if x.Mode == "async" && x.Action != "observe" {
		return errors.New("异步模式只能观察")
	}
	if x.Enabled && len(x.KnowledgeBaseIDs) == 0 {
		return errors.New("启用策略前至少选择一个知识库")
	}
	if x.TopK == 0 {
		x.TopK = 4
	}
	if x.MaxClaims == 0 {
		x.MaxClaims = 8
	}
	if x.SupportThreshold == 0 {
		x.SupportThreshold = 70
	}
	if x.EvidenceThreshold == 0 {
		x.EvidenceThreshold = .35
	}
	if x.TopK < 1 || x.TopK > 10 || x.MaxClaims < 1 || x.MaxClaims > 20 || x.SupportThreshold < 0 || x.SupportThreshold > 100 || x.EvidenceThreshold < 0 || x.EvidenceThreshold > 1 {
		return errors.New("事实核验阈值无效")
	}
	return nil
}

const policySelect = `SELECT id::text,scope,enabled,mode,action,knowledge_base_ids::text[],support_threshold,evidence_threshold,top_k,max_claims,revision,created_at,updated_at FROM gateway.fact_check_policies`

func scanPolicy(row pgx.Row) (Policy, error) {
	var x Policy
	err := row.Scan(&x.ID, &x.Scope, &x.Enabled, &x.Mode, &x.Action, &x.KnowledgeBaseIDs, &x.SupportThreshold, &x.EvidenceThreshold, &x.TopK, &x.MaxClaims, &x.Revision, &x.CreatedAt, &x.UpdatedAt)
	if errors.Is(err, pgx.ErrNoRows) {
		err = ErrNotFound
	}
	return x, err
}
func (s *Service) Policies(ctx context.Context) ([]Policy, error) {
	rows, err := s.pool.Query(ctx, policySelect+` ORDER BY scope`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	items := []Policy{}
	for rows.Next() {
		x, err := scanPolicy(rows)
		if err != nil {
			return nil, err
		}
		items = append(items, x)
	}
	return items, rows.Err()
}
func (s *Service) SavePolicy(ctx context.Context, x Policy, actor string) (Policy, error) {
	if err := validatePolicy(&x); err != nil {
		return Policy{}, err
	}
	if x.KnowledgeBaseIDs == nil {
		x.KnowledgeBaseIDs = []string{}
	}
	if x.ID == "" {
		x.ID, _ = platformid.NewUUID()
		_, err := s.pool.Exec(ctx, `INSERT INTO gateway.fact_check_policies(id,scope,enabled,mode,action,knowledge_base_ids,support_threshold,evidence_threshold,top_k,max_claims,created_by) VALUES($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11)`, x.ID, x.Scope, x.Enabled, x.Mode, x.Action, x.KnowledgeBaseIDs, x.SupportThreshold, x.EvidenceThreshold, x.TopK, x.MaxClaims, actor)
		if err != nil {
			return Policy{}, err
		}
	} else {
		tag, err := s.pool.Exec(ctx, `UPDATE gateway.fact_check_policies SET scope=$2,enabled=$3,mode=$4,action=$5,knowledge_base_ids=$6,support_threshold=$7,evidence_threshold=$8,top_k=$9,max_claims=$10,revision=revision+1,updated_at=clock_timestamp() WHERE id=$1`, x.ID, x.Scope, x.Enabled, x.Mode, x.Action, x.KnowledgeBaseIDs, x.SupportThreshold, x.EvidenceThreshold, x.TopK, x.MaxClaims)
		if err != nil {
			return Policy{}, err
		}
		if tag.RowsAffected() == 0 {
			return Policy{}, ErrNotFound
		}
	}
	return scanPolicy(s.pool.QueryRow(ctx, policySelect+` WHERE id=$1`, x.ID))
}
func (s *Service) DeletePolicy(ctx context.Context, id string) error {
	tag, err := s.pool.Exec(ctx, `DELETE FROM gateway.fact_check_policies WHERE id=$1`, id)
	if err != nil {
		return err
	}
	if tag.RowsAffected() == 0 {
		return ErrNotFound
	}
	return nil
}

type Event struct {
	ID           string          `json:"id"`
	PolicyID     *string         `json:"policy_id"`
	RequestID    string          `json:"request_id"`
	Model        string          `json:"model"`
	Mode         string          `json:"mode"`
	Action       string          `json:"action"`
	Verdict      string          `json:"verdict"`
	SupportScore *int            `json:"support_score"`
	LatencyMS    int             `json:"latency_ms"`
	Question     string          `json:"question,omitempty"`
	Answer       string          `json:"answer,omitempty"`
	Claims       json.RawMessage `json:"claims,omitempty"`
	Evidence     json.RawMessage `json:"evidence,omitempty"`
	Error        string          `json:"error"`
	CreatedAt    time.Time       `json:"created_at"`
}

const eventSelect = `SELECT id::text,policy_id::text,request_id,model,mode,action,verdict,support_score,latency_ms,question,answer,claims,evidence,error,created_at FROM gateway.fact_check_events`

func scanEvent(row pgx.Row) (Event, error) {
	var x Event
	err := row.Scan(&x.ID, &x.PolicyID, &x.RequestID, &x.Model, &x.Mode, &x.Action, &x.Verdict, &x.SupportScore, &x.LatencyMS, &x.Question, &x.Answer, &x.Claims, &x.Evidence, &x.Error, &x.CreatedAt)
	if errors.Is(err, pgx.ErrNoRows) {
		err = ErrNotFound
	}
	return x, err
}
func (s *Service) Events(ctx context.Context, verdict string, limit int) ([]Event, error) {
	if limit < 1 {
		limit = 50
	}
	if limit > 200 {
		limit = 200
	}
	query := eventSelect
	args := []any{}
	if verdict != "" {
		args = append(args, verdict)
		query += ` WHERE verdict=$1`
	}
	args = append(args, limit)
	query += ` ORDER BY created_at DESC LIMIT $` + strconv.Itoa(len(args))
	rows, err := s.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	items := []Event{}
	for rows.Next() {
		x, err := scanEvent(rows)
		if err != nil {
			return nil, err
		}
		x.Question = ""
		x.Answer = ""
		x.Claims = nil
		x.Evidence = nil
		items = append(items, x)
	}
	return items, rows.Err()
}
func (s *Service) Event(ctx context.Context, id string) (Event, error) {
	return scanEvent(s.pool.QueryRow(ctx, eventSelect+` WHERE id=$1`, id))
}